1. Field of the Invention
The present invention relates to an attachment system for adjusting the clearance between an impeller and a suction housing of a standard impeller pump.
2. Background of the Prior Art
In a typical impeller pump the bearing housing and the bearing frame are two separate items attached to one another. A first series of generally evenly spaced apart bolts, typically three in number and referred to as attaching bolts, pass through the bearing housing and are threadably received within the bearing frame. A second series of generally spaced apart (from each other and from the first series of bolts) bolts, also typically three in number and referred to as held bolts, pass threadably through the bearing housing and abut the bearing frame. The clearance achieved between the bearing housing and the bearing frame (the impeller clearance) is on the order of a fraction of an inch with the precise clearance being pump size and model specific. The first series of bolts and the second series of bolts cooperatively work to achieve the desired clearance. Tightening of the first series of bolts draws the impeller closer to the bearing frame while tightening the second series of bolts moves the bearing housing further from the suction housing. Applying the proper torque to each series of bolts will produce the appropriate push and pull forces on the pump elements (shaft, bearings, impeller, and bearing housing) such that the desired clearance between the impeller, being held bearing housing via a shaft and bearing, and the suction housing that is attached to the bearing frame, is achieved and the pump operates with maximum efficiency.
If the bolts are torqued to factory specifications, the shaft acts as a lever and loads the floating bearing and angularly mis-aligns the held bearing. This removes the running clearance between the rotating balls of the bearing and the inner and outer races of the bearing greatly reducing the running life of the bearing. This also causes the pump to work hard and thereby operate less efficiently.
Therefore, there is a need in the art for a mechanism that will provide for the appropriate adjustment in order to achieve the appropriate clearance between the impeller and the suction housing without preloading the bearings. The mechanism must be simple in design and must be quick and easy to use. The device must not rely on specialized tools such as torque wrenches in order to achieve the desired result. The mechanism should be usable on newly manufactured pumps as well as pumps already installed in the field.
The impeller clearance adjustment system of the present invention addresses the aforementioned needs in the art. The device provides for a mechanism that allows quick, easy and accurate adjustment of the clearance between the impeller and the suction housing of an impeller pump without the need for a torque wrench or other specialized tool. The impeller clearance adjustment system can be implemented on newly manufactured pumps and can also be retrofit installed in existing pumps in the field.
The impeller clearance adjustment system is comprised of a first housing having a plurality of spaced apart first openings. A second housing has a plurality of spaced apart second openings registerable with the plurality of first openings. A plurality of twinserts are each received within one of the plurality of second openings. A plurality of adjustment bolts are provided, each bolt passes through a first opening in the bearing housing and abuts against a face of a twinsert. A bore opening passes through the central axis of each adjustment bolt. An attachment bolt passes through the opening of each adjustment bolt and is threadably received within the twinsert. The use of the twinsert allows for retrofit installment of the impeller clearance adjustment system of the present invention to be installed on existing pumps in the field. Once each bolt is properly positioned, the clearance between the impeller and the suction housing is established. Thereafter, each attachment bolt is tightened while the adjustment bolt is held. This simultaneous tightening ensures that the impeller does not move relative to the suction housing thereby maintaining the desired impeller clearance.